Good luck with the project. There are a couple of local guys here making replica racers. One is modeled on the Amon Stuck car and the other modeled on the blue Gitanes racer. Both are exciting projects hoping to be ready by the end of the year.
Apart from the roll cage what chassis strengthening are you doing?
Next week, on my shell, I will be adding a diff reinforcement plate and seam welding this area, gusseting brackets in the engine bay from the chassis rails to the firewall, stitch welding in the usual suspect areas of the body and a few plug welds here and there.